ci: Gitea pipeline — gate on both self-hosted runners, publish alpha releases

Every push to main now runs the gate on the self-hosted runners and, when
green, publishes a Gitea Release carrying the client, launcher+bake, and
manifest.

Pipeline (.gitea/workflows/ci.yml):
- windows-gate runs tools/run-release-gate.ps1, the project's own bounded
  gate. A bare `dotnet test AcDream.slnx` is NOT usable as a gate: it fails
  ~36 tests by design, because the InstalledDat/Live/Manual/OS lanes assert
  their own preconditions. The gate script's trait filter is what excludes
  them.
- linux-portable runs the portable closure, where the Linux-lane tests
  actually execute instead of failing on Windows.
- release depends on both, so a red gate cannot publish. It is a job in the
  same workflow rather than a workflow_run trigger, whose Forgejo support is
  unreliable; `needs` is guaranteed.

No actions/setup-dotnet: data.forgejo.org does not mirror it at all (404),
and both runners carry the pinned SDK band already. actions/checkout IS
mirrored and is used normally.

Release payloads become release ATTACHMENTS, outside git history, so ~120 MB
per build never enters a branch. Only the ~500-byte manifest.json is
committed, to the payload-free dist branch, because Forgejo has no
/releases/latest/download/ route (verified 404) for the launcher to poll.
publish-bin.ps1 takes -BaseUrl so the manifest points at the release tag.

Two real gate failures fixed:
- LauncherProjectBoundaryTests asserted four `**` path filters belonging to
  the push triggers that 8be14d39 removed when workflows went manual-only.
  The assertions about what the workflow DOES are untouched.
- MainWindowViewTests failed in Test Case Cleanup with "calling thread cannot
  access this object" while passing in isolation: Avalonia's headless session
  is thread-affine and xUnit ran collections in parallel. Serialized via
  xunit.runner.json, the same settings AcDream.Core.Tests already uses.

Local gate: 12 projects, 14,346 tests, 0 failures.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tools/publish-bin.ps1

@@ -34,6 +34,7 @@
 [CmdletBinding()]
 param(
     [string]$Version,
+    [string]$BaseUrl,
     [switch]$IncludeLinux,
     [string]$MinimumLauncherVersion = '0.0.1'
 )
@@ -61,9 +62,16 @@ foreach ($candidate in @($Version, $MinimumLauncherVersion)) {
     }
 }
 
-# Raw-file base for the PUBLIC Gitea repo's dist branch. Must agree with
-# ReleaseManifestClient.ProductionManifestUri.
-$RawBase = 'https://git.snakedesert.se/erik/acdream/raw/branch/dist/bin'
+# Where the manifest says the payloads live. The CI pipeline passes the Gitea
+# RELEASE asset base for the tag it is publishing, so payloads live outside git
+# entirely; the default keeps the older dist-branch layout working for a manual
+# local publish. The manifest itself always stays at the stable dist raw URL
+# that ReleaseManifestClient.ProductionManifestUri points at.
+$RawBase = if ([string]::IsNullOrWhiteSpace($BaseUrl)) {
+    'https://git.snakedesert.se/erik/acdream/raw/branch/dist/bin'
+} else {
+    $BaseUrl.TrimEnd('/')
+}
 
 $BinRoot = Join-Path $RepoRoot 'bin'
 $Staging = Join-Path $BinRoot 'payload'